Propeller clamping and balancing ring



June 15, 1937. J. E. LARASON 2,083,569

PROPELLER CLAMPING AND BALANCING RING Filed Marcfi 25, 1955 INVENTOR JOHN E. LA/QASO/V TOAIVEXY Patented June 15, 1937 UNITED STATES PATENT} OFFICE PROPELLER CLAMPING AND BALANCING RING John E. Larason, Dayton, Ohio Application Mai-ch25, 1935, Serial No. 12,900

2 Claims.

(Granted under the act of March 3, 1883, as

' amended April 30, 1928; 3'70 0. G. 757) necessitate two balancing operations before.

placement of an assembled propeller upon an 15 aircraft engine. Having accomplished the first of these operations; i. e., vertical balance of the propeller, in the usual manner, it is a principal object of my invention to proceed with horizontal balance of said propeller without adversely 20 affecting the aforementioned vertical balance. These adjustments are found to be necessary for both the fixed and controllable pitch propellers.

- With the foregoing and other objects-in View,

which will appear as the description proceeds, 25 the invention consists of certain'new and novel improvements in propeller clamp and balancing rings, which will be hereinafter more fully illustrated and described inthe accompanying drawing and more particularly pointed out in the 30 appended claims. Referring to the drawing, in which numerals of like character designate similar parts throughout the several claims:

Fig. 1 is a partial side view of a propeller in- 35 corporating my invention;

Fig. 2-is a cross-sectional view taken on the line 2-2 of Fig. 1.

My invention is shown by way of illustration in Figs. 1 and 2. It is well known that propeller 40 blades of the controllable type have. a tendency to change their angular positions or pitch and turn towards a neutral position either when revolving as an increased or reversed'pitch propeller. This is partly due to the centrifugal 45 force acting upon the different individual propellers through their respective moment arms resulting in a turning force on the blade about its longitudinal axis tending to align the blade with the plane of rotation. It is also partly due to 0 the air resistance on the trailing side of the blade being slightly larger than the air rw'istance on the leading side of the blade in the usual construction. To overcome these undesirable forces,

the blades are provided with counterbalancing;

55 means such as counterweights of well-known construction that neutralize or counterbalance the combined effect of the centrifugal forces and the aerodynamic forces acting on the propeller blades and thereby offset the unbalanced twisting condition so that the blades will tend to retain their respective angular position in whatever pitch they may be set whilethus rotating. The addition of these counterweights does not, however, overcome the effects due to a statically unbalanced propeller of which these counterweights constitute a part. As previously employed these counterweights were fixed to the propeller at predetermined points. In accordance with prior teachings the reversible pitch propellers require in addition .to such counterbalancing further means for effecting vertical and lateral balance of the blades of the propeller and for this, purpose various manufactm'ing"expedieiicies were resorted to to obtain proper balance, such, for example, as of brazing of gobs or masses of metal to the internal structure of the blade at desired points for effecting the balance. In accordance with my inventio n the counterbalancing means serves a two-fold function, that of statically balancing the blade for vertical and lateral balance and that of dynamically balancing the blade.

The construction of my novel adjusting means, as illustrated in Figs. 1 and 2, is identical to that shown and described in my Patent No. 1,995,312, except that instead of arranging the adjusting means on the blade socket portions of. the hub, the adjusting means is arranged at the shank portion of the blades and that, therefore, instead of providing the socket portions with shoulders the blades are formed with shoulders 4', which serve to limit the outward movement of the split ring 5a and 5b. This embodiment is further distinguished in that the clamping ring 1' on each blade is provided with a mass that is made an integral part thereof.

Thus the clamping ring 1' of each blade not only counteracts centrifugal and aerodynamic forces, but also serves, when adjusted laterally relative to the corresponding split ring 51: and 5b, to vary the vertical balance of the propeller and when adjusted rotationally together with the split ring 5a and 5b to vary the vertical balance.

By suitably adjusting the lateral and longitudinal'relation of the clamping ring 1' and the split ring 50. and 5b with respect to any one or more of the blades, the horizontal or vertical balance of the propeller is accomplished.

This application is a continuation in part of my co-pending application filed March 20, 1934, Serial Number'716,509, now Reissued Patent No.

2 0 20,159 (original No. 1,995,312, dated March 26,

\1935) reissued November 3, 1936.

balancing means for each blade radially disposed with respect to the axis of rotation of said propeller on said blade, each of said balancing means including an inner ring member and a counterweight member, said members being relatively adjustable laterally with respect to each other for obtaining a horizontal balance and angularly adjustable together for obtaining a vertical balance, and means for locking said members to each other and to said blade.

2. In combination, a propeller having a hub,

a plurality of blades, said blades being revolvably mounted on said hub about an axis perpendicular to the axis of rotation of said hub and means for eflfecting vertical and horizontal balance of said propeller and-for neutralizing the turning eflfect on the blades due to centrifugal and aerodynamic forces comprising separate counterweight balancing means for each blade,

each or said means including a ring member mounted for rotational movement about said vertical axis and a counterweight supported by said ring member, said counterweight being displaceable along said vertical axis relative to said ring -member and movable therewith angularly, and means for locking said counterweight and ring member to one another and to said propeller.

JOHN E. LARASON. 

